Abstract: Apparatus for forming a pocketed spring unit, comprising a plurality of strings of pocketed springs and at least one cover sheet, comprises welding tools for welding together the pocketing material and the sheet. One of the welding tools is provided with a cutter for cutting the pocket prior to welding. The tool travels in the direction of Arrow A1, so that the cutter penetrates the pocketing material substantially centrally at the circular proximal end face of the pocket. Once inside the pocket, the tool moves axially through the centre of the spring until it reaches the distal end face of the pocket. Before the end face is reached, the piercing member becomes retracted in the direction of Arrow A2, so that the blade does not pierce the distal end face of the pocket.

Abstract: A pocketed spring unit comprises a plurality of strings of pocketed springs and a cover sheet, wherein each string comprises a flap of material located along an edge of the string and extending longitudinally of the string. The cover sheet is attached to the flaps at welds W.